Capstan assembly and control system

ABSTRACT

A method and apparatus for precisely controlling the tension of a cabling assembly is described. The control loop includes a triple-feedback-loop to allow the manufacture of a large number of cable pairs. The control loop may be used with any take-up and payoff assemblies and compensate for wide variations in take-up reel weight, cable weight, process line speeds, and pay-off tension. One of the loops of the triple-feedback-loop is under-damped and unstable and allows the control loop to compensate for the wide variations without changing control systems or cabling apparatus.

BACKGROUND

[0001] In today's modern environment, it is common to findcommunications-grade cable running by the mile through buildings,between cities, and even across oceans. Communications cables and othermiscellaneous cables are found in nearly every household and building tofacilitate the transfer of information, images, and other data acrossany distance at ever-increasing speeds.

[0002] Apparatuses for manufacturing communications and other types ofcables of various kinds have been known for some time. One well-knownmethod of cabling is the use of a capstan/dancer/pay-off reel assembly.According to a conventional capstan/dancer/pay-off reel assembly (2)shown in FIG. 1, a plurality of wire pairs (4) are wound on a capstandrum (6). The wire pairs (4) are usually unwound from the capstan drum(6) and introduced through a dancer (8). The dancer (8) is usually amovable roller or set of rollers that applies a constant tension to thewire pairs (4). The dancer (8) may also cable the wire pairs into asingle cable strand (10), often in a helical configuration. The singlecable strand (10) produced by the capstan (4) and dancer (8) is thenusually wound onto a take-up or pay-off reel (12).

[0003] One of the most difficult tasks in producing high-qualitycommunications cables is balancing the tension of the cable strand thatis wound onto the pay-off reel with the tension added to the wire pairsby the dancer. The pay-off reel must be carefully controlled to apply aconstant tension to the finished cable equal to the tension added by thedancer. However, as the finished cable is wound onto the pay-off reel,the weight of the pay-off reel changes, adding to the difficulty ofmaintaining balanced tension between the cable and the wire pairs.Usually no more than four wire pairs can be cabled into high-gradecommunication cables because of the difficulty maintaining tensionbalance.

[0004] This difficulty may be further explained by a simple analogy.Many vehicles include a “cruise control” feature intended to enable adriver to maintain a constant speed over long travel distances. However,the course of travel often includes hills and valleys that require thevehicle engine to compensate for the power requirements necessary tomaintain a constant speed over the hills and through the valleys.Driving along relatively small hills and valleys, most vehicles canmaintain the pre-selected speed within about five percent. However, onlarger hills, it is common for the speeds to vary by ten to twentypercent or more because the vast changes in power demanded to maintain aconstant speed.

[0005] Similarly, as cables are manufactured, the weight of the pay-offreel is constantly changing. The motor driving the pay-off reel mustcompensate for changes in reel weight as the cable is produced tomaintain a constant tension in the produced cable in order tomanufacture a cable of high quality. While a ten to twenty percentvariation in speed may be adequate for most vehicles, such a significantvariation in the tension of a sensitive communication cable may renderthe cable useless. Exacerbating the difficulty of maintaining a constantcable tension is a demand for the production of more and more wiringpairs into a single cable. The variation in pay-off reel weight fromstart to finish may vary by hundreds or thousands of percent.

[0006] The current approach to the problem of balancing produced-cabletension with wire pair tension is to provide an electronic loop thatmonitors pay-off reel motor speed. The electronic loop provides feedbackto a controller, which then attempts to adjust the power to the pay-offreel motor to maintain a constant cable-line speed. However, the signalsprovided by the electronic loop must generally be conditioned so thatthey remain stable. The conditioned signals are thus damped and resultin a limited control range. Typical single-control loops do not providethe capability of manufacturing cables from high numbers of wire pairswhile maintaining a tension balance between the wire input side of thedancer and the cable output side of the dancer. Therefore, according tothe current state of the art, very few pairs (usually four or less) ofwires can be effectively cabled in to high-grade communications cables.

[0007] Further, typical cabling machinery and controls are designed forspecific product types, processed under conditions unique to theparticular product type. For those who manufacture multiple producttypes, multiple sets of machinery-each dedicated to a particularproduct-are required. Alternatively, in some instances a single set ofmachinery is used for multiple product types, but significantmodifications and/or extensive machine set-ups must be done each time aproduct is changed.

SUMMARY OF THE INVENTION

[0008] In one of many possible aspects, the present invention provides acabling control system including a first cabling control loop, a secondcabling control loop, and a third cabling control loop. The firstcabling control loop may be under-damped and unstable.

[0009] Another aspect of the present invention provides a cablingassembly including: a frame, a capstan drum assembly supported by theframe, a drum drive motor coupled to the drum assembly, a dancerassembly spaced from the capstan drum assembly, a take-up reel, and atriple-loop control system for controlling cabling from the capstan drumassembly to the take-up reel.

[0010] Another aspect of the present invention provides a capstanapparatus including: a take-off reel assembly supported by a frame, atake-off reel drive motor coupled to the take-off reel assembly andadapted to provide a supply of wire pairs at a constant rate, a dancerassembly spaced from the take-off reel assembly and adapted to receivethe supply of wire pairs at the constant rate, a pay-off reel, and acapstan controller including a triple-loop feedback system forcontrolling cabling from the take-off reel assembly to the pay-off reel.

[0011] Another aspect of the present invention provides a method ofcontrolling cabling equipment including applying a triple-loop feedbackmechanism to a cabling controller.

[0012] Another aspect of the present invention provides a method ofcontrolling a cabling assembly including providing a triple-loopfeedback mechanism.

[0013] Another aspect of the present invention provides a method ofcreating a cable including unreeling multiple wires to a dancer assemblyat a constant rate, applying a constant tension to the multiple wires,and cabling the elements onto a take-up reel, wherein the constanttension of the elements is precisely controlled by atriple-feedback-loop.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings illustrate various aspects of thepresent invention and are a part of the specification. Together with thefollowing description, the drawings demonstrate and explain theprinciples of the present invention. The illustrated aspects areexamples of the present invention and do not limit the scope of theinvention.

[0015]FIG. 1 is a diagram of a conventional cabling assembly.

[0016]FIG. 2 is a front view of a capstan assembly according to oneaspect of the present invention.

[0017]FIG. 3 is a side view of the capstan assembly of FIG. 2 accordingto one aspect of the present invention.

[0018]FIG. 4 is a diagrammatical representation of a cabling and controlsystem according to one aspect of the present invention.

[0019]FIG. 5 is diagrammatical representation of the control loop of acabling system according to one aspect of the present invention.

[0020] Throughout the drawings, identical reference numbers designatesimilar, but not necessarily identical, elements. While the invention issusceptible to various modifications and alternative forms, specificaspects have been shown by way of example in the drawings and will bedescribed in detail herein. However, it should be understood that theinvention is not intended to be limited to the particular formsdisclosed. Rather, the invention is to cover all modification,equivalents and alternatives falling within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION OF ASPECTS OF THE INVENTION

[0021] Turning now to the figures, and in particular to FIGS. 2-3, afront and side view of a cabling assembly (20) according to one aspectof the present invention is shown. The cabling assembly (20) of thepresent aspect includes a frame such as the metal support frame (22)shown. Mounted to the support frame (22) is a capstan drum assembly(24). The capstan drum assembly (24) may have any number of wire pairswound thereon for producing a cable. For example, in some aspects thecapstan drum assembly (24) has as few as two wire pairs, in others itmay have as many as twenty-five pairs or more.

[0022] The capstan drum assembly (24) is coupled to a capstan drum drivemotor (26) that provides rotational power to the capstan drum assembly(24). The capstan drum assembly (24) and the capstan drum drive motor(26) are commercially available from a variety of sources.

[0023] The capstan drum drive motor (26) is controlled to provide thewire pairs from the capstan drum assembly (24) to a dancer assembly (28)at a constant rate. The power provided by the capstan drum drive motor(26) may vary as the wire pairs are unwound from the capstan drumassembly (22) and the weight of the capstan drum assembly (22)decreases.

[0024] The dancer assembly (28) is supported by the support frame (22)and spaced from the capstan drum assembly (22) according to the presentaspect. Alternatively, the dancer assembly (28) may include a separatesupport frame. The dancer assembly (28) includes a roller (30) slidinglymounted along first and second guides (32 and 34). The roller (30) maytherefore travel linearly along the guides (32 and 34), as well a rotateabout a shaft (36). The dancer assembly (28) provides a constant tensionto the wiring pairs that extend from the capstan drum (24) and aroundthe roller (30). The constant tension is facilitated by a cylindermounted between the roller (30) and the support frame (22). The cylinderof the present aspect is a pneumatic cylinder (38) that provides aconstant force to the roller (30). The constant force causes the roller(30) to move along the guides (32 and 34) to keep the tension in thewire pairs extending from the capstan drum assembly (24) substantiallyconstant.

[0025] Air or other gas for the pneumatic cylinder (38) may be suppliedat a constant pressure by a supply cylinder (40) mounted to the supportframe (22). In addition, an air assembly (42) may be mounted to thesupport frame (22) to provide air to the supply cylinder (40) at aconstant pressure and may include a gauge (44) and filter (46).

[0026] A position sensor, which monitors and reports position, is alsomounted between the dancer assembly (28) and the support frame (22).According to the present aspect of the invention, the position sensor isa linear potentiometer (48). The linear potentiometer (48) iscommercially available from many sources and provides for accuratemeasurement of the position of the dancer assembly (28).

[0027] As mentioned above, the cabling assembly (20) of the presentaspect may include many wiring pairs to generate a communication cable.In some aspects, the cabling assembly (20) may hold up to twelve wiringpairs. In other aspects the cabling assembly (20) may include up totwenty-five wiring pairs or more. In addition, multiple cablingassemblies (20) may be linked together in series to create cables withany number of strands. For example, four cabling assemblies (20) oftwenty-five wiring pairs each may be arranged in series to produce aone-hundred strand cable. Ever more cabling assemblies (20) may bearranged in series or parallel to create cables of six-hundred strandsor more. However, the cabling assemblies (20) need not be the same, orhold the same number of wiring pairs.

[0028] While the control of the cabling assembly (20) to facilitateprecise tension control for high numbers of wiring pairs has not beenpossible in the past, a control system according to one aspect of thepresent invention enables precise control of multiple cabling assemblies(20) with high numbers (twelve or more) of wire pairs. Of course thecontrol system described above may also be used to control low numbersof wire pairs.

[0029] Turning next to FIG. 4, a representation of a cabling controlsystem (100) according to one aspect of the present invention is shown.The cabling control system (100) is shown coupled to a capstan, forexample the cabling assembly (20) described above. The cabling assembly(20) may be a first or master capstan apparatus as shown in FIG. 4. Thedetails of the master capstan apparatus are discussed above withreference to FIGS. 2 and 3. An optional second capstan, for example aslave capstan apparatus (120), is also shown coupled to the cablingcontrol system (100) according to the aspect of FIG. 4. The slavecapstan apparatus (120) may be similar or identical to the mastercabling apparatus (20), but this is not necessarily so. The slavecapstan apparatus (120) and master cabling apparatus (20) may differ instructure in some aspects. Further, in some aspects, the slave capstanapparatus (120) is omitted altogether, and in other aspects, the slavecapstan apparatus (120) is representative of a plurality of many slavecapstans, each controlled by the cabling control system (100). Thenumber of capstans may vary from a single master cabling apparatus (20)to dozens of capstans or more.

[0030] The master cabling apparatus (20) is electrically connected viaan interface (106) to a master capstan controller (108). The mastercapstan controller (108) may include a commercially availableprogrammable motor controller, such as a programmable DC (directcurrent) motor controller. Similarly, as shown in the aspect of FIG. 4,the slave capstan apparatus (120) (if any) may include a communicationinterface (112) to a slave capstan controller (110). The slave capstancontroller (110) may include a commercially available programmable motorcontroller similar or identical the master capstan controller (108). Inaspects with more than one slave capstan (104), each slave capstan mayinclude a slave capstan controller (110) or they may all be controlledby the master capstan controller (108).

[0031] A plurality of wire pairs (114 and 116) from the master cablingapparatus (20) and the slave capstan apparatus (120) may be cabled andintroduced to a take-up reel (118). The take-up reel (118) includes acommunication interface (121) to a take-up controller and motor (122)according to one aspect of the present invention. The take-up controllerand motor (122), the master capstan controller (108), and the slavecapstan controller (110) are each in communication with a programmablelogic controller (“PLC”) (124). The take-up controller and motor (122)is programmed and controlled by the PLC (124) via a communicationinterface (126). Similarly, the master and slave capstan controllers(108 and 110) are also programmed and controlled by the PLC (124) viatwo additional communications interfaces (128 and 130). The PLC (124) iscommercially available from a variety of sources.

[0032] The PLC (124) may be communicably connected via an interface(132) to a human machine interface (134). As with the PLC (124), thehuman machine interface (134) is commercially available from a varietyof sources. The human machine interface (134) facilitates programming ofthe PLC (124) by a user and may include a keyboard, mouse, display,touch-screen, and/or other human machine interfaces.

[0033] In some aspects, the PLC (124) may also be operatively connectedto a safety function interface (136). The safety functions interface(136) may be used to monitor characteristics of the cabling/capstanapparatus (e.g. 20 and 120) and/or the take-up reel (118) and cause thePLC to shut the capstans (20 and 120) and take-up reel (118) down whencertain parameters are met. For example, the safety function interface(136) may monitor motor current of the take-up reel (118) and/or thecapstan drum drive motor (26, FIG. 2) of the capstan assemblies (20 and120). The safety function interface (136) may also monitor feedbacksignals to ensure that they are within realistic ranges. Further, thesafety function interface (136) may monitor the feedback signals toensure that they change regularly (an extended period without anychanges may indicate a problem). The safety function interface may alsomonitor production speed, take-up reel speed, and/or capstan drum (24)speeds to ensure that the cabling operation is functioning withinacceptable limits. The safety function interface (136) may also monitorthe cabling assemblies (20 and 120) and their components, as well as thetake-up reel, for possible misplacements. The monitoring formisplacements may be facilitated by one or more photo eyes operativelyconnected to the safety function interface (136). The safety functioninterface (136) may also include any other monitors as desired to checkfor anything abnormal in the cabling process and shut the system (100)down in the event that any monitored parameter exceeds (or falls under)a predetermined threshold programmed into the safety function interface(136) or the PLC (124).

[0034] The cabling control system (100) may include a plurality ofcontrol loops to facilitate the production of a cable (138). Accordingto the aspect of FIG. 4, the cabling control system (100) is atriple-loop configuration. The triple-loop control system shownprimarily controls the tension of wires being cabled, which in turndetermines the quality of the cable produced. The more closely balancedthe tension on each side of the dancer assemblies (28/128) is, thebetter the quality of the cable. However, as discussed above, it may beextremely difficult or impossible with conventional cabling controlsystems to balance the tension between the dancer assemblies (28/128)and the take-up reel (118) with the tension applied by the dancerassemblies (28/128) to the wires pairs being cabled from the capstandrum (24/124). The tension of the cable (138) downstream of the dancerassemblies (28/128) is a function of the take-up reel (118) rotation.And as the take-up reel (118) fills with cable (138), it comes more andmore difficult to maintain a constant take-up reel (118) speed orconstant cable (138) line speed—especially for cables made of a dozen ormore wire pairs. A high number of wire pairs (e.g. a dozen or more)creates a wide variation in weight between an empty pay-off reel and afull pay-off reel.

[0035] Therefore, in order to facilitate cabling of high numbers of wirepairs, a triple-loop control configuration is used. A triple-loopcontrol configuration (200) according to one aspect of the presentinvention is shown in FIG. 5. The triple-loop control loop configuration(200) as shown may be programmed into the PLC (124, FIG. 4) by those ofskill in the art having the benefit of this disclosure. The triple-loopcontrol configuration (200) includes three distinct control loops.

[0036] A first control loop is an underdamped feedback loop (202).Because the first control loop is underdamped, it tends to be unstable,but highly sensitive to changes. According to the present aspect, theunder-damped feedback loop (202) monitors and compensates for variationsin take-up reel (118) weight. The under-damped feedback loops (202)feeds back to the PLC (124, FIG. 2) armature current of a take up reeldrive motor (204). As the cable (138) is manufactured, it winds up onthe take-up reel (118). The take-up reel (118) therefore increases inweight as the cable (138) is produced. Accordingly, the take-up reeldrive motor (204) must continuously adjust to provide a constant tensionto the cable (138) as it traverses the dancer (28) of the cablingassembly (20). The tension in the cable (138) must be quite precise forcommunications cables and other sensitive cables to ensure the qualityof the cable (138). In some aspects, the cable (138) may be made from upto twelve pairs of wires, up to twenty-five pairs of wires, up toone-hundred pairs of wires, up to about six-hundred pairs of wires, oreven more. For example a set of four cabling assemblies (20, 120, etc.),each having twenty-five wire pairs of may be operatively connected toone another and controlled by the triple-loop control system (200) tocreate a one-hundred strand cable.

[0037] Therefore, the challenge of compensating for weight variations ina cable with many pairs of wires is considerable prior to the presentinvention. Accordingly, present invention uses the triple-loop feedbackcontrol system (200) to enable precise control of wide ranges of cablesizes and wide ranges in the number of wiring pairs being cabled.

[0038] As will be understood by those of skill in the art having thebenefit of this disclosure, the introduction of the first under-dampedfeedback loop (202) can advantageously adjust quickly to wide variationsin take-up reel (118) weight as a cable of many strands is produced. Thefirst under-damped feedback loop (202) may also be used to monitor andadjust for other cabling components. A transfer function (208) isapplied to the first under-damped feedback loop (202) to condition thesignal indicating armature current drawn by the take-up reel drive motor(204). The transfer function according to one aspect of the presentinvention is: $\begin{matrix}\frac{K_{A}\left( {1 + {s\quad \tau_{A1}}} \right)}{\left( {1 + {s\quad \tau_{A2}}} \right)} & (1)\end{matrix}$

[0039] where, according to standard notation:

[0040] K_(A) is a physical constant that does not change and isrepresentative of the cabling equipment;

[0041] s is a LaPlace transform; and

[0042] τ_(A1) and τ_(A2) are changing constants based on changes in thetake-up reel (118) weight.

[0043] It is readily apparent to those of skill in the art having thebenefit of this disclosure that equation (1) represents an under-dampedtransfer function, and therefore provides an unstable feedback loop thatwould not be used according to conventional control practice because ofthe potential for loss of control of the control loop (200). It is alsoapparent to those of skill in the art having the benefit of thisdisclosure that other under-damped transfer functions may be applied tothe first feedback loop (202) to increase the range of accurate controlson high numbers of wire pairs being cabled, and that equation (1) isexemplary in nature. That is, the present invention is not limited tothe transfer function of equation (1).

[0044] The first under-damped feedback loop (202) may compensate fortake-up reel (118) weight variations for up to about six hundred paircable configurations or even more. By compensating for take-up reel(118) weight variations, the first under-damped feedback loop (202)adjusts for tension imbalances between the wire pairs (114) and themanufactured cable (138) and causes a torque to be applied to thetake-up reel (118) as necessary to balance the tensions. According tothe triple-loop control system (200) of the present invention, there isno theoretical limit to the number of wire pairs that can be effectivelycabled. However, because the first feedback loop (202) is unstable,according to one aspect of the present invention, there are twoadditional feedback loops facilitating tension balance of the wires(114) and the cable (138) before and after the dancer assembly (28). Theadditional feedback loops ensure control of the cabling equipment(Capstan assemblies (20 and 120), dancer (28) take-up reel (118), etc.)without compromising the added benefit of the first unstable feedbackloop (202) to facilitate precise control over a high number of wirepairs being cabled.

[0045] A second control loop of the two additional feedback loops is aneutrally stable feedback loop (208). According to the aspect shown, thesecond neutrally stable feedback loop (208) monitors and compensates forvariations in cable (138) line speed and/or reel (118) speed duringcabling operation. However, the second neutrally stable feedback loop(208) may also monitor and compensate for other cabling operationparameters.

[0046] As discussed above, because of the increasing weight on thepay-off reel (118) during cabling operation, the line speed and/or reelspeed tends to change without feedback-control of the take-up reel drivemotor (204). The neutrally stable feedback loop (208) feeds back to thePLC (124, FIG. 2) actual motor speed of the take-up reel drive motor(204), the take-up reel (118) speed, and/or the cable line speed. Astension imbalances are detected and fed-back, a measured torque may beapplied to the pay-off reel (118) to balance the tensions.

[0047] As also discussed above, when the cable (138) is manufactured, itwinds up around the take-up reel (118). The take-up reel thereforeincreases in weight as the cable (138) is produced. Accordingly, atake-up reel drive motor (204) must continuously adjust to provide aconstant speed to the take-up reel in order to impart a constant tensionto the cable (138) as it traverses a dancer (28) of the cabling assembly(20). While the second neutrally stable feedback loop (208) is not assensitive to changes in cable (138) tension by monitoring take-up motordrive (204) speed, take-up reel speed, and/or cable (138) line speed asthe first unstable feedback loop (202), it provides a stable additionalinput to the first unstable feedback loop (202) to prevent the cableproduction process from going out of control (as may happen otherwisewith feedback from only the unstable feedback loop (202)). In addition,the actual take-up motor speed, take-up reel speed, and/or line speed istypically a good indicator of cable (138) tension, and therefore feedingback the speed of the motor, reel, and/or line to the PLC (124, FIG. 4)adds to the precision of the control system (200).

[0048] A second transfer function (228) is applied to the secondneutrally stable feedback loop (208) to condition the signal reported bythe second feedback loop (208) indicative of cable line speed, take-updrive motor speed, and/or reel speed. The transfer function according toone aspect of the present invention is: $\begin{matrix}\frac{K_{V}\left( {1 + {s\quad \tau_{V1}}} \right)}{\left( {1 + {s\quad \tau_{V2}}} \right)} & (2)\end{matrix}$

[0049] where, according to standard notation:

[0050] K_(V) is a physical constant that does not change and isrepresentative of the cabling equipment;

[0051] s is a LaPlace transform; and

[0052] τ_(V1) and τ_(V2) are changing constants based on changes in theweight of the take-up reel (118).

[0053] It is readily apparent to those of skill in the art having thebenefit of this disclosure that equation (2) represents a criticallydamped to slightly under-damped transfer function, and thereforeprovides the neutrally stable second feedback loop (208). It is alsoapparent to those of skill in the art having the benefit of thisdisclosure that other neutrally stable transfer functions may also beapplied to the second feedback loop (208), and that equation (2) isexemplary in nature. That is, the present invention is not limited tothe transfer function of equation (2) but may use any function causingcritical-to-slightly under-damping.

[0054] A third control loop of the two additional feedback loops is anunconditionally stable loop (230) according to some aspects of theinvention. The third stable feedback loop (230) monitors and compensatesfor variations in dancer assembly (28) position. As the tension on thepay-off reel (118) side of the dancer assembly (28) tends to fluctuatewith the increasing weight of the pay-off reel (118), the position ofthe dancer assembly (28) changes to maintain a constant tension on thewire pairs (114) coming from the take-off reel (24). Therefore, changesin position of the dancer assembly (28) may indicate a tension imbalanceacross the dancer assembly (28).

[0055] Accordingly, the third stable feedback loop (230) feeds back tothe PLC (124, FIG. 2) the dancer assembly (28) position according to thepresent aspect. The third stable feedback loop (230) may feedback otheraspects of the cabling equipment including, but not limited to thosementioned with reference to the first two feed back loops. Theinformation from the third stable feedback loop (230) may be taken intoaccount to adjust the control of the take-up reel drive motor (204) toprovide a constant tension to the cable (138) on the pay-off reel (118)side of the dancer assembly (28) by applying a certain torque to thepay-off reel (118) by the take-up reel drive motor (204). While thethird stable feedback loop (230) is not as sensitive to changes in cable(138) tension by monitoring dancer position as the first unstablefeedback loop (202), it provides another stable input to the first andsecond feedback loops (202 and 208). The additional feedback loop (230)may prevent the cable production process from going out of control andallow for more precise tension control of the produced cable (138). Theadditional precision comes as the additional input on the dancer (28)position is compensated for. However, because the second neutrallystable feedback loop (208) and the third stable feedback loop (230) aredamped significantly more than the first unstable feedback loop (202),neither the second or third feedback loops—alone or in combination—canprovide the range and flexibility of the triple-loop configurationsincluding the first feedback loop (202).

[0056] A third transfer function (232) is applied to the third stablefeedback loop (230) to condition the signal reported by the thirdfeedback loop (230) indicative of dancer assembly (28) position. Thetransfer function according to one aspect of the present invention is:$\begin{matrix}\frac{K_{P}\left( {s\quad \tau_{P1}} \right)}{\left( {1 + {s\quad \tau_{P2}}} \right)} & (3)\end{matrix}$

[0057] where, according to standard notation:

[0058] K_(P) is a physical constant that does not change and isrepresentative of the cabling equipment;

[0059] s is a LaPlace transform; and

[0060] τ_(P1) and τ_(P2) are changing constants based on the weight ofthe take-up reel (118).

[0061] It is readily apparent to those of skill in the art having thebenefit of this disclosure that equation (3) represents an overdampedtransfer function, and therefore provides the unconditionally stablethird feedback loop (230). It is also apparent to those of skill in theart having the benefit of this disclosure that other stable transferfunctions may also be applied to the third feedback loop (230), and thatequation (3) is exemplary in nature. That is, the present invention isnot limited to the transfer function of equation (3).

[0062] According to the present aspect of the triple-loop control system(200), the overall loop damping ratio is about 0.74 across allcombinations of variations in reel weight, reel fill, and line speed.The triple-loop control system (200) may advantageously be used for anycabling equipment, and is not limited to the cabling assembly (20)described above. The triple-loop feedback system compensates for widevariations in take-up reel (118) weight, cable weight, process linespeeds, and pay-off tension automatically. Thus a single set of machines(such as cabling assembly (20)) may be used to process a multitude ofproducts at varying speeds.

[0063] In addition, the control system of the present invention is notlimited to only three control loops. Additional control loops may alsobe added to further enhance the control of the cabling assembly (20).There may be four or more control loops according to some aspects of theinvention. Additional control loops may, for example, monitor and report“jerk” (rapid acceleration changes).

[0064] The preceding description has been presented only to illustrateand describe aspects of invention. It is not intended to be exhaustiveor to limit the invention to any precise form disclosed. Manymodifications and variations are possible in light of the aboveteaching.

[0065] The foregoing aspects were chosen and described in order toillustrate principles of the invention and some practical applications.The preceding description enables others skilled in the art to utilizethe invention in various aspects and with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the following claims.

What is claimed is:
 1. A cabling control system comprising: a firstcabling control loop, a second cabling control loop, and a third cablingcontrol loop.
 2. The system of claim 1, where the first cabling controlloop comprises an underdamped unstable control loop.
 3. The system ofclaim 2, wherein the unstable control loop comprises a first feedbackloop monitoring a take-up reel motor armature current.
 4. The system ofclaim 3, wherein the first feedback loop compensates for variations intake-up reel weight during cabling operation.
 5. The system of claim 4,wherein the first feedback loop compensates for dancer tensionimbalances while processing up to about 600 pair cable configurations.6. The system of claim 5, wherein the first feedback loop compensatesfor dancer tension imbalances while processing up to about 100 pair ofcable configurations.
 7. The system of claim 2, wherein the secondcabling control loop comprises a neutrally stable control loop.
 8. Thesystem of claim 7, wherein the neutrally stable control loop iscritically damped to slightly underdamped.
 9. The system of claim 7,wherein the neutrally stable control loop comprises a second feedbackloop and monitors take-up reel drive motor speed.
 10. The system ofclaim 7, wherein the neutrally stable control loop comprises a secondfeedback loop and compensates for variations in line speed or take-upreel speed, or both, during cabling operation.
 11. The system of claim7, wherein the third cabling control loop comprises a stable controlloop.
 12. The system of claim 11, wherein the third stable control loopis overdamped.
 13. The system of claim 12, wherein the third stablecontrol loop comprises a third feedback loop that monitors andcompensates for changes in dancer position.
 14. The system of claim 11,wherein the overall loop damping ratio is approximately 0.74 across allcombinations or variations in reel weight, reel fill, and line speed.15. The system of claim 1, further comprising a capstan and dancerassembly coupled to the first, second, and third control loops.
 16. Thesystem of claim 15, further comprising a plurality of capstan and dancerassemblies coupled to the first, second, and third control loops.
 17. Acabling assembly comprising: a frame; a capstan drum assembly supportedby the frame; a drum drive motor coupled to the drum assembly; a dancerassembly spaced from the capstan drum assembly; a take-up reel; and atriple-loop control system for controlling cabling from the capstan drumassembly to the take-up reel.
 18. The assembly of claim 17, furthercomprising a pneumatic cylinder for maintaining a constant tension oncables between the drum assembly and the dancer assembly.
 19. Theassembly of claim 18, further comprising a linear potentiometer formonitoring the position of the dancer assembly.
 20. The assembly ofclaim 17, wherein the capstan and dancer assemblies contain up totwenty-five cable pairs.
 21. The assembly of claim 20, wherein thetriple-loop control system comprises a controller having an underdampedfirst feedback loop.
 22. The assembly of claim 21, wherein theunderdamped first feedback loop is programmed to monitor take-up reelmotor armature current and compensate for variations in take-up reelweight.
 23. The assembly of claim 21, wherein the triple-loop controlsystem further comprises a second critically damped-to-underdampedfeedback loop programmed to compensate for variations in line speed,take-up reel speed, or both, that arise as the take-up reel fills withcable.
 24. The assembly of claim 23, wherein the triple-loop controlsystem further comprises a third overdamped feedback loop programmed tocompensate for variations in dancer assembly position.
 25. A capstanapparatus comprising: a take-off reel assembly supported by a frame; atake-off reel drive motor coupled to the take-off reel assembly andadapted to provide a supply of wire pairs at a constant rate; a dancerassembly spaced from the take-off reel assembly and adapted to receivethe supply of wire pairs at the constant rate; a pay-off reel; and acapstan controller comprising a triple-loop feedback system forcontrolling cabling from the take-off reel assembly to the pay-off reel.26. The apparatus of claim 25, wherein the triple-loop feedback systemcomprises an underdamped first feedback loop.
 27. The apparatus of claim26, wherein the underdamped first feedback loop is programmed to monitorpay-off reel motor armature current.
 28. The apparatus of claim 25,further comprising a programmable logic controller for programming andcontrolling the capstan controller.
 29. The apparatus of claim 28,further comprising a user interface coupled to the programmable logiccontroller.
 30. The apparatus of claim 25, further comprising one ormore additional slave capstan controllers controlling one or moreadditional capstan apparatuses.
 31. The apparatus of claim 25, furthercomprising a safety functions interface programmed to monitor one ormore capstan apparatus parameters and shut down the capstan apparatuswhen the one or more parameters reach a predetermined threshold.
 32. Theapparatus of claim 31, wherein the one or more capstan assemblyparameters comprise pay-off reel motor current, feedback signal ranges,time period between changes in feedback signals, position of the dancerassembly, and pay-off reel speed.
 33. A method of controlling cablingequipment comprising applying a triple-loop feedback mechanism to acabling controller.
 34. The method of claim 33, wherein the applying thetriple-loop further comprises compensating for weight variations in atake-up reel by feeding back motor armature current of a take-up reeldrive motor with an underdamped first feedback loop.
 35. The method ofclaim 34, wherein the applying a triple loop further comprisescompensating for cable line speed, take-up reel speed, or both, byfeeding back take-up reel motor speed with a neutrally stable secondfeedback loop.
 36. The method of claim 35, wherein the neutrally stablesecond feedback loop comprises critically damping or slightlyunderdamping a signal indicative of the take-up reel motor speed. 37.The method of claim 35, wherein the applying a triple loop furthercomprises compensating for tension differences between a wire input sideof a dancer and a wire output side of the dancer by feeding back dancerposition with an overdamped third feedback loop.
 38. The method of claim33, further comprising providing an overall loop damping ratio of 0.74across all combinations of variations in reel weight, reel fill, andline speed.
 39. A method of controlling a cabling assembly comprisingproviding a triple-loop feedback mechanism.
 40. The method of claim 39,further comprising conditioning a first loop of the triple-loop feedbackmechanism with an underdamped transfer function.
 41. The method of claim40, wherein the first loop monitors take-up reel motor armature currentand compensates for variations in take-up reel weight.
 42. The method ofclaim 40, further comprising conditioning a second loop of thetriple-loop feedback mechanism with a critically damped-to-slightlyunderdamped transfer function.
 43. The method of claim 42, wherein thesecond loop monitors take-up motor speed and compensates for variationsin line speed, reel speed, or both as a take-up reel fills with cable.44. The method of claim 42, further comprising conditioning a third loopof the triple-loop feedback mechanism with an overdamped transferfunction.
 45. The method of claim 44, wherein the third loop monitors adancer assembly position and compensates for differences in tensionbetween a wire input side of the dancer and a cable output side of thedancer.
 46. The method of claim 45, further comprising applying torqueto a take-up reel to balance the differences in tension.
 47. A method ofcreating a cable comprising: unreeling multiple wires to a dancerassembly at a constant rate; applying a constant tension to the multiplewires; and cabling the elements onto a take-up reel; wherein theconstant tension of the elements is precisely controlled by atriple-feedback-loop.
 48. The method of claim 47, wherein thetriple-feedback loop comprises an underdamped first loop feeding take-upmotor armature current back to a controller and compensating forvariations in take-up reel weight.
 49. The method of claim 48, whereinthe triple-feedback loop comprises a critically damped second loopfeeding take-up motor speed to the controller and compensating forvariations in line speed, reel speed, or both.
 50. The method of claim49, wherein the triple-feedback loop comprises an overdamped third loopfeeding dander position to the controller and compensating fordifferences in tension between a wire input side of the dancer assemblyand a wire output side of the dancer assembly.
 51. A cabling assemblycomprising: a capstan drum assembly; a take-up reel; and a triple-loopcontrol system for controlling cabling from the capstan drum assembly tothe take-up reel.
 52. The assembly of claim 51, further comprising apneumatic cylinder for maintaining a constant tension on cables betweenthe capstan drum assembly and a dancer assembly arranged between thecapstan drum assembly and the take-up reel.
 53. The assembly of claim51, wherein the triple-loop control system comprises a controller havingan underdamped first feedback loop.
 54. The assembly of claim 53,wherein the underdamped first feedback loop is programmed to monitortake-up reel motor armature current and compensate for variations intake-up reel weight.